ABSTRACT
As we calculate analytic to link the coefficient of third-order polynomial equations from raw data of an Asean to the SEIR model. The Reproductive index depending on the average incubation period and the average infection period and the coefficient polynomial equations fitted from raw are derived . We also consider the difference of the average incubation period as 5 days and 3 days with the average infection period as 10 day of an Asean. We find that the value of are Indonesia (7.97), Singapore (6.22), Malaysia (3.86), Thailand (2.48), respectively. And we also find that Singapore has 2 values of as 1.54 (16 Feb to 37 March) and 6.22 (31 March-4 April).The peak of infection rate are not found for Singapore and Indonesia at the time of consideration. The model of external stimulus is added into raw data of Singapore and Indonesia to find the maximum rate of infection. We find that Singapore need more magnitude of external stimulus than Indonesia. And the external stimulus for 14 days can stimulate to occur the peak of infected daily case of both country.